History-chasing Serena already best ever: analysts

NEW YORK (Reuters) - Serena Williams is on the brink of a crowning achievement in tennis, but as far as several top analysts are concerned, the 33-year-old American has already established herself as the greatest women's player ever.

Williams would become only the fourth woman to sweep all four grand slams in a season should she win a fourth consecutive U.S. Open title in the tournament starting on Monday.

"To me, she's the greatest female player that every played," seven-times slam winner John McEnroe said about the holder of each of the slam titles following 2015 wins at the Australian, French and Wimbledon championships and her 2014 U.S. victory.

Former doubles specialist Pam Shriver said Williams' performance this year moved her to rank the American ahead of 18-times grand slam champion Martina Navratilova.

"This year I’ve put her as my all-time great," Shriver told Reuters. "She's still winning so many majors, so many more than anyone else in their 30s. She's won them in the '90s, 2000s and now - three different decades."

Williams would join Maureen Connolly (1953), Margaret Court (1970) and Steffi Graf (1988) as the only women to register a Grand Slam. A U.S. Open win would tie her with Graf on the grand slam title list with 22, two behind all-time leader Court.

Williams, with no clear rival in sight, has won 28 grand slam matches in a row, 21 consecutive contests at the U.S. Open and 44 in a row on U.S. hardcourts.

"It's pretty remarkable," said former player and U.S. Fed Cup coach Mary Joe Fernandez, who like McEnroe and Shriver serve as commentators for U.S. Open broadcaster ESPN.

"The fact that she’s still so strong at nearly 34 years of age ... impresses me the most," she told Reuters.

Shriver said the fact that Williams has dominated this year despite not playing at her best underlines her greatness.

"The way her year has gone it has been anything but routine in the majors. She’s lost nine sets. It’s been a huge struggle but she has somehow found a way in her mid 30s to win all these pressure situations," said Shriver.

"One of the great measures of a champion is that they can still win and even win major titles when they are not playing their best."

McEnroe said Williams has gotten better with age. "She's better in every way now. She's more prepared now.